This invention relates to saw chain sharpening machines, and more particularly relates to sharpening machines having means for holding the chain securely and firmly during the sharpening operation and means for automatically advancing the chain stepwise on the holder for sharpening all its cutter elements.
In sharpening a saw chain, the chain is commonly mounted on a support such that its cutter elements are positioned in an upright manner for sharpening by a grinding means such as a dressed or shaped grinding disc or wheel. The support is usually in the form of a groove holder having an open end groove therein. The chain is placed upon the support with its central drive links extending downwardly into the groove and the side plates of each link riding on the two sides of the groove. The chain may thus be slidably moved along the groove for positioning its cutter elements one by one consecutively for sharpening by the grinding disc or discs. Since the grinding disc exerts a considerable force in the transverse direction to the chain, the cutter element being sharpened tends to move sideways. Such sideways movement of the cutter element during the sharpening operation can greatly affect the accuracy of the surface being sharpened.
Clamping means have been used for securely holding the cutter element while it is being sharpened. However, known clamping means are either complex in structure or time consuming to operate. Furthermore, such clamping means usually provide gripping on the central drive links or the side plates of the links, and they often cause distortion or breakage in these elements in the chain.
In some sharpening machines, a latch finger is incorporated on the holder for abutting the cutter element in the side opposite to the cutter surface in order to reduce the sideway movement of the cutting element while it is being sharpened. However, such latch finger either does not provide satisfactory anchoring to prevent the sideway movement or is difficult to operate.
Also, heretofore the advancement of the chain in sharpening machines is carried out manually. The operator must repeat the steps of positioning the cutter elements one by one in a sharpening station and positioning the grinding disc in the cutter element thus positioned for sharpening. Such repeating operations are both tedious and time consuming to carry out.